Novak Djokovic eased to victory at the Cincinnati Open in his first singles match in the United States in two years.
The 23-times Grand Slam champion had been unable to compete in the US over Covid protocols.
But rules for unvaccinated foreign travellers were relaxed in May, enabling him to return to competition.
He won the first set 6-4 against Spain's Alejandro Davidovich Fokina, who later retired with a back issue.
The victory was the 36-year-old's Serb's first-time playing singles in Cincinnati since 2019. However, on Tuesday, he lost in doubles when he and compatriot Nikola Cacic were beaten by Britain's Jamie Murray and Michael Venus of New Zealand.
Elsewhere, Australian qualifier Max Purcell beat third seed Casper Ruud in three sets for his first victory over a top-10-ranked player.
Purcell, the world number 70, saved six out of seven break points to win 6-4 3-6 6-4 and set up a meeting with three-time Grand Slam winner Stan Wawrinka.
The Swiss former world number three continued his return to form with a 6-3 6-4 win over American 16th seed Frances Tiafoe.
Sixth seed Jannik Sinneralso bowed out, losing 6-4 7-6 (7-1) to Serbian Dusan Lajovic.
Russian third seed Daniil Medvedev moved into the last 16 with a 6-3 6-2 win over Italy's Lorenzo Musetti.
Medvedev, who claimed the title in 2019 before reaching the US Open final, faces Germany's Alexander Zverev next.
